Initial commit

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/protocol.h

@@ -0,0 +1,81 @@
+#pragma once
+
+// What the game and the server agree on. The server hands out lobby codes, keeps each lobby's members and passes
+// WebRTC signaling between them; matches themselves run peer to peer. Messages are JSON objects with a "type":
+//
+// Game to server:
+//   create  {name, version}         make a lobby and join it as host
+//   join    {code, name, version}   join a lobby by its code
+//   leave   {}                      leave the lobby
+//   kick    {id, reason}            (the host) put someone out of the lobby
+//   signal  {to, payload}           pass a WebRTC description or candidate to another member
+//   ping    {}                      keeps the connection alive through proxies (answered with pong)
+//
+// Server to game:
+//   welcome      {id, code, host, members: [{id, name}]}   in a lobby (members includes this one)
+//   member_join  {id, name}
+//   member_leave {id, host, kicked?, reason?}              host is who hosts now; kicked says they were kicked
+//   kicked       {reason}                                  this member was kicked out of the lobby
+//   signal       {from, payload}
+//   error        {message}                                 the request failed; the connection stays open
+//   pong         {}
+//
+// A signal's payload is either a description {sdp, kind} or a candidate {candidate, mid}.
+
+#include <string>
+#include <string_view>
+
+constexpr int PROTOCOL_VERSION = 2;
+constexpr int LOBBY_MEMBERS_MAX = 4;
+constexpr int LOBBY_CODE_LENGTH = 4;
+// Letters only, without I and O, so codes are easy to read out and type.
+constexpr const char LOBBY_CODE_LETTERS[] = "ABCDEFGHJKLMNPQRSTUVWXYZ";
+constexpr int PLAYER_NAME_MAX = 24;
+constexpr int CHAT_MESSAGE_MAX = 100;
+constexpr int KICK_REASON_MAX = 60;
+constexpr const char SERVER_URL_DEFAULT[] = "wss://shweetz.net/smack-a-brother/ws";
+constexpr int SERVER_URL_LENGTH = 128;
+
+// Text from elsewhere (another player, or the server) made safe to show: only printable ASCII (what the game's font
+// has; anything else, emoji included, is dropped), cut to max characters, with spaces at its ends trimmed.
+inline std::string text_clean(std::string_view raw, size_t max)
+{
+    std::string text;
+    for (char c : raw)
+        if (c >= ' ' && c <= '~' && text.size() < max)
+            text += c;
+    size_t first = text.find_first_not_of(' ');
+    size_t last = text.find_last_not_of(' ');
+    return first == std::string::npos ? "" : text.substr(first, last - first + 1);
+}
+
+// A count of seconds in words: "1 second", "29 seconds".
+inline std::string seconds_say(int seconds)
+{
+    return std::to_string(seconds) + (seconds == 1 ? " second" : " seconds");
+}
+
+// A string as a JSON string literal, quotes included.
+inline std::string json_quote(const std::string& text)
+{
+    std::string quoted = "\"";
+    for (unsigned char c : text)
+        if (c == '"' || c == '\\')
+            quoted += '\\', quoted += (char)c;
+        else if (c == '\n')
+            quoted += "\\n";
+        else if (c == '\r')
+            quoted += "\\r";
+        else if (c == '\t')
+            quoted += "\\t";
+        else if (c < 0x20)
+        {
+            constexpr char HEX[] = "0123456789abcdef";
+            quoted += "\\u00";
+            quoted += HEX[c >> 4];
+            quoted += HEX[c & 15];
+        }
+        else
+            quoted += (char)c;
+    return quoted + "\"";
+}